ABSTRACT
Low-level river crossings are important for delivering a range of important socioeconomic services, including transportation and hydrological control. In natural rivers and hydraulic structures, including culverts, water in motion is turbulent. Turbulent flows are characterized by an unpredictable pseudo-random behavior, strong mixing properties, and a broad spectrum of length and time scales. Although the turbulence may be analyzed in terms of the statistical properties of the velocity components, the turbulence scales are of interest in addition to the turbulence intensity and statistical moments of the turbulent velocity fluctuations. Turbulent vortical structures span over a wide hierarchy of scales, which are all important to turbulent flow science. Existing culvert guidelines for upstream fish passage are typically based upon a number of simple criteria, including bulk velocity and minimum water depth. The safety of the embankment depends to a large extent upon the stability of the culvert structure.
